A magnetoencephalographic study of face processing: M170, gamma-band oscillations and source localization

Authors

  • Zaifeng Gao,

    1. Department of Psychology, Zhejiang University, Hangzhou, People's Republic of China
    2. Department of Psychology, The Hebrew University of Jerusalem, Jerusalem, Israel
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  • Abraham Goldstein,

    1. Department of Psychology and Gonda Brain Research Center, Bar-Ilan University, Ramat Gan, Israel
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  • Yuval Harpaz,

    1. Department of Psychology and Gonda Brain Research Center, Bar-Ilan University, Ramat Gan, Israel
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  • Myriam Hansel,

    1. Department of Psychology, The Hebrew University of Jerusalem, Jerusalem, Israel
    2. Department of Psychology and Gonda Brain Research Center, Bar-Ilan University, Ramat Gan, Israel
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  • Elana Zion-Golumbic,

    1. Department of Psychiatry, Columbia University Medical Center, New York, New York, USA
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  • Shlomo Bentin

    Corresponding author
    1. Department of Psychology, The Hebrew University of Jerusalem, Jerusalem, Israel
    2. Interdisciplinary Center for Neural Computation, The Hebrew University of Jerusalem, Jerusalem, Israel
    • Department of Psychology, The Hebrew University of Jerusalem, Israel
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Abstract

EEG studies suggested that the N170 ERP and Gamma-band responses to faces reflect early and later stages of a multiple-level face-perception mechanism, respectively. However, these conclusions should be considered cautiously because EEG-recorded Gamma may be contaminated by noncephalic activity such as microsaccades. Moreover, EEG studies of Gamma cannot easily reveal its intracranial sources. Here we recorded MEG rather than EEG, assessed the sources of the M170 and Gamma oscillations using beamformer, and explored the sensitivity of these neural manifestations to global, featural and configural information in faces. The M170 was larger in response to faces and face components than in response to watches. Scrambling the configuration of the inner components of the face even if presented without the face contour reduced and delayed the M170. The amplitude of MEG Gamma oscillations (30–70 Hz) was higher than baseline during an epoch between 230–570 ms from stimulus onset and was particularly sensitive to the configuration of the stimuli, regardless of their category. However, in the lower part of this frequency range (30–40 Hz) only physiognomic stimuli elevated the MEG above baseline. Both the M170 and Gamma were generated in a posterior-ventral network including the fusiform, inferior-occipital and lingual gyri, all in the right hemisphere. The generation of Gamma involved additional sources in the visual system, bilaterally. We suggest that the evoked M170 manifests a face-perception mechanism based on the global characteristics of face, whereas the induced Gamma oscillations are associated with the integration of visual input into a pre-existent coherent perceptual representation. Hum Brain Mapp, 2013. © 2012 Wiley Periodicals, Inc.

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